Wellington, Nov 30 (IANS): New Zealand scientists have unlocked the mystery of why so many cancer patients die of blood clots while undergoing chemotherapy in a study.

Chemotherapy stimulates release of tiny bubbles from the surface of cancer cells, causing the potentially fatal clots, said the study by University of Otago researchers that came out on Wednesday, Xinhua news reported.

Most deaths from cancer were caused by uncontrolled growth of tumour in vital organs, but the second most common way that cancer kills is by triggering blood clotting resulting in thrombosis.

The clots cause blockage of major blood vessels, preventing oxygen and nutrients to vital organs.

Despite being life-prolonging, chemotherapy is thus associated with a six-to-seven fold increase in the risk of thrombosis in cancer patients.

The link between cancer and thrombosis was noted over 100 years ago, but the reasons for the association had been elusive, Associate Professor Alex McLellan said in a statement.

McLellan's team discovered cancer cells treated with chemotherapy releasing lipid-rich bubbles from their membranes that activated coagulation (clotting) processes.

"We now have insight into how these bubbles from dying cancer cells may cause thrombosis during chemotherapy," McLellan said.

The research had showed that certain solid cancers were more active in promoting blood coagulation, as compared to lymphomas.

"A general pattern is that cancers such as pancreatic, lung and brain cancers carry the largest risk of thrombotic events," he said.

The study opened the possibility of developing inhibitors to the major coagulation pathway identified in cancer cells.